A coupling device of this type has become known from DE-C2-36,23,367. The prior-art coupling device is used to connect a tube to the pipe socket of an anesthesia device or respirator. On its inside, the tube has a locking member which is designed as an elastic lip and snaps into an undercut when pushed over the pipe socket. The coupling device is designed such that even though the tube is in firm contact with the pipe socket during respiration, it is possible to rapidly remove the tubes from the pipe socket in the case of an emergency. The locking member is expanded radially by the axial pulling force acting on the tube to the extent that it will slide out of the undercut and the coupling device will thus be detached.
Coupling devices have also been known from the connection of respiration tubes in gas masks and breathing apparatus. It is required here for the respiration tubes to be firmly connected to the corresponding pipe socket during operation, but rapid separation is desirable during the preparation of the apparatus for use. To achieve this, the tube is firmly clamped onto the corresponding pipe socket, which means a large amount of mounting work. However, the tube may be damaged by tightening the clamps too tightly, and it is often difficult to work with a tool in breathing apparatus of compact design.
A quickly detachable coupling described in DE-C3,26,57,215 consists of a pipe socket that is provided with a circumferential notch and a tube with a coupling box, at the end of which opposite projecting parts, which snap into the notch of the pipe socket in the assembled state, are provided. The coupling box is made of elastic material in the area of the projecting parts and is provided with pressure-absorbing areas which are arranged offset by 90.degree. in relation to the projecting parts. On compression of the pressure-absorbing areas, the coupling box is expanded to the extent that the projecting parts will slide out of the notch.
Even though the prior-art coupling permits the tube and pipe socket to be joined rapidly, the connection is able to absorb only limited pulling-off forces. The outer, flexible part of the coupling box expands radially and the projecting parts slide out of the notch in the case of stronger pulling-off forces. In addition, such a coupling is expensive to manufacture, because complicated plastic parts, which are shaped correspondingly to fit one another and must be manufactured with close tolerances, are needed.